1. Field of the Invention
The invention in general relates to hydrophones, and in particular to a broadband low frequency magnetostrictive dipole hydrophone.
2. Description of the Prior Art
Dipole hydrophones, or receivers, respond to the pressure gradient of the acoustic wave in the medium in which it is operating and provide signals proportional to the particle velocity of the acoustic wave. A unique feature of a dipole hydrophone is its figure-8, or cosine directivity pattern. Such hydrophones find use not only in air, such as for example microphones, but also find use in the underwater environment for listening to low frequency noise, as may be produced by a submarine, for example.
Various dipole hydrophones have constructional limitations which would prevent their use under water. For example, some dipole hydrophones not only provide an output signal proportional to the ambient medium particle velocity, but also provide an unwanted output signal in response to hydrophone movement -- that is, acceleration. The dipole hydrophone of the present invention produces a low frequency broadband dipole acoustic pattern, is rugged and economical to build, and has a long time reliability for in situ operations. In addition, force or moment inputs causing rectilinear or rotational acceleration are effectively cancelled.